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We define the notion of ordinal computability by generalizing standard Turing computability on tapes of length ω to computations on tapes of arbitrary ordinal length. We show that a set of ordinals is ordinal computable from a finite set of ordinal parameters if and only if it is an element of Gödel's constructible universe L. This characterization can be(More)
Spectral water vapor transmission of the bands between 0.7 microm and 1 microm is determined from ground-based measurements of direct solar radiation with a high resolution grating spectrometer. These transmission values are compared with those published by Moskalenko, which are the only spectral water vapor data below 1 microm applicable to real(More)
Scattering functions, i.e., the scattered intensity as a function of angle, are modeled for tropospheric aerosol types with respect to the effect of the nonspherical shape of the particles. Scattering functions of nonspherical particles compared with those of equivalent spheres show differences increasing with particle size. Thus, for aerosol types with a(More)
The Naproche project 1 (NAtural language PROof CHEcking) studies the semi-formal language of mathematics (SFLM) as used in journals and textbooks from the perspectives of linguistics, logic and mathematics. A central goal of Naproche is to develop and implement a controlled natural language (CNL) for mathematical texts which can be transformed automatically(More)
The method of vicarious calibration by means of calculated radiances allows absolute calibration of satellite radiometers in orbit. It works by comparing counts from the radiometer to be calibrated with corresponding absolute radiances, calculated from actual values of the relevant optically acting parameters of the atmosphere and the earth's surface. The(More)
BACKGROUND Both cigarette smoke and ultraviolet (UV) radiation are known to cause changes of the skin which can be regarded as premature ageing. OBJECTIVES To assess the theory that the effects of these two exposures could be linked by a phototoxic action of cigarette smoke. METHODS A photohaemolysis test was used, in which human erythrocytes were(More)